WMPoweruser.com is reporting that technical writer Charles Petzold is writing a book detailing developing for the Windows Phone 7 operating system.  He has chosen to release a draft version, weighing in at 153 pages, in ebook format.

This is a great opportunity for anyone interested in developing for the upcoming Windows Phone 7 platform, as you can get a practical look at how Silverlight and XNA will be used for the phones, complete with code samples.

If you are interested, you can download the ebook in XPS format here or in PDF format here.  You can also download the code samples referenced in the book here.